Hybrid logic and SRAM contacts

ABSTRACT

The method includes forming a first opening in a dielectric layer exposing a source drain region of an SRAM device and forming a second opening in the dielectric layer exposing a source drain region of a logic device, forming a third opening in the dielectric layer exposing a gate of the SRAM device and forming a fourth opening in the dielectric layer exposing a gate of the logic device, forming a first sidewall spacer in the third opening and forming a second sidewall spacer in the fourth opening, recessing a portion of the first sidewall spacer without recessing the second sidewall spacer, forming a strapped contact in the first and third openings, the strapped contact creates an electrical connection between the source drain region of the SRAM device and the gate of the SRAM device, the electrical connection is directly above a remaining portion of the first sidewall spacer.

BACKGROUND

The present invention generally relates to semiconductor manufacturing,and more particularly to fabricating electrically insulated contacts ofa logic device and a strapped contact of a static random access memory(hereinafter “SRAM”) device in the same process flow.

Complementary Metal-oxide-semiconductor (CMOS) technology is commonlyused for fabricating field effect transistors (FET) as part of advancedintegrated circuits (IC), such as central processing units (hereinafter“CPUs”), memory, storage devices, and the like. Different CMOS devicesmay be fabricated with different contact arrangements based on theirintended use and function. For example, an SRAM device may be fabricatedwith a strapped contact in which an electrically conductive bridge isformed between a source/drain contact and a gate contact. Conversely, alogic device may be fabricated with source/drain contacts which areelectrically insulated from a gate contact.

SUMMARY

According to an embodiment of the present invention, a method isprovided. The method may include forming a first opening in a dielectriclayer which exposes a source drain region of an SRAM device and forminga second opening in the dielectric layer which exposes a source drainregion of a logic device, forming a third opening in the dielectriclayer which exposes a gate of the SRAM device and forming a fourthopening in the dielectric layer which exposes a gate of the logicdevice, forming a first sidewall spacer in the third opening and forminga second sidewall spacer in the fourth opening, recessing a portion ofthe first sidewall spacer without recessing the second sidewall spacer,forming a strapped contact in the first and third openings, the strappedcontact creates an electrical connection between the source drain regionof the SRAM device and the gate of the SRAM device, the electricalconnection is directly above a remaining portion of the first sidewallspacer, and forming contacts in the second and fourth openings, thesecond sidewall spacer electrically isolates the contact of the secondopening from the contact of the fourth opening.

According to another embodiment, a method is provided. The method mayinclude forming a first opening in a dielectric layer which exposes asource drain region of an SRAM device and forming a second opening inthe dielectric layer which exposes a source drain region of a logicdevice, forming a first contact in the first opening and forming asecond contact in the second opening, forming a third opening in thedielectric layer which exposes a gate of the SRAM device and a sidewallof the first contact, and forming a fourth opening in the dielectriclayer which exposes a gate of the logic device, forming a first sidewallspacer in the third opening and forming a second sidewall spacer in thefourth opening, the first sidewall spacer being in direct contact withthe sidewall of the first contact, recessing a portion of the firstsidewall spacer to expose the sidewall of the first contact, withoutrecessing the second sidewall spacer, forming a third contact in thethird opening, abutting the sidewall of the first contact, such that thesource drain region of the SRAM device is in electrical contact with thegate of the SRAM device, and forming a fourth contact in the fourthopening, the second sidewall spacer electrically isolates the secondcontact from the fourth contact.

According to another embodiment, a structure is provided. The structuremay include a logic device including a first contact and a secondcontact, the first contact is above and in electrical contact with agate of the logic device, the second contact is above and in electricalcontact with a source drain of the logic device, the first contact iselectrically isolated form the second contact by a sidewall spacer abovethe gate, and a static random access memory (SRAM) device including athird contact and a fourth contact, the third contact is above and inelectrical contact with a gate of the SRAM device, the fourth contact isabove and in electrical contact with a source drain of the SRAM device,a portion of a sidewall of the third contact is in direct contact with aportion of a sidewall of the fourth contact such that the gate and thesource drain, both of the SRAM device, are electrically connected.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description, given by way of example and notintended to limit the invention solely thereto, will best be appreciatedin conjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a semiconductor structure at anintermediate stage of fabrication, according to an exemplary embodiment;

FIG. 2 is a cross-sectional view of the semiconductor structure andillustrates forming a first opening and a second opening, according toan exemplary embodiment;

FIG. 3 is a cross-sectional view of the semiconductor structure andillustrates filling the first opening and the second opening, accordingto an exemplary embodiment;

FIG. 4 is a cross-sectional view of the semiconductor structure andillustrates forming a third opening and a fourth opening, according toan exemplary embodiment;

FIG. 5 is a cross-sectional view of the semiconductor structure andillustrates forming a pair of sidewall spacers within the third openingand forming a pair of sidewall spacers within the fourth opening,according to an exemplary embodiment;

FIG. 6 is a cross-sectional view of the semiconductor structure andillustrates recessing the pair of sidewall spacers in the third openingwithout recessing the pair of sidewall spacers in the fourth opening,according to an exemplary embodiment;

FIG. 7 is a cross-sectional view of the semiconductor structure andillustrates forming a gate contact structures in the third opening andin the fourth opening according to an exemplary embodiment;

FIG. 8 is a top view of a semiconductor structure depicted in FIG. 7,according to an exemplary embodiment;

FIG. 9 is a cross-sectional view of the semiconductor structure at anintermediate stage of fabrication in which the first and second openingsare filled with a sacrificial material, according to another exemplaryembodiment;

FIG. 10 is a cross-sectional view of the semiconductor structure andillustrates forming a third opening and a fourth opening, according toan exemplary embodiment;

FIG. 11 is a cross-sectional view of the semiconductor structure andillustrates forming a pair of sidewall spacers within the third openingand forming a pair of sidewall spacers within the fourth opening,according to an exemplary embodiment;

FIG. 12 is a cross-sectional view of the semiconductor structure andillustrates recessing the pair of sidewall spacers in the third openingwithout recessing the pair of sidewall spacers in the fourth opening,according to an exemplary embodiment;

FIG. 13 is a cross-sectional view of the semiconductor structure andillustrates removing the sacrificial material from within the firstopening and from within the second opening, according to an exemplaryembodiment;

FIG. 14 is a cross-sectional view of the semiconductor structure andillustrates forming source drain contact structures in the first andsecond openings and forming gate contact structures in the third andfourth openings according to an exemplary embodiment; and

FIG. 15 is a top view of a semiconductor structure depicting in FIG. 14,according to an exemplary embodiment.

Elements of the figures are not necessarily to scale and are notintended to portray specific parameters of the invention. For clarityand ease of illustration, scale of elements may be exaggerated. Thedetailed description should be consulted for accurate dimensions. Thedrawings are intended to depict only typical embodiments of theinvention, and therefore should not be considered as limiting the scopeof the invention. In the drawings, like numbering represents likeelements.

DETAILED DESCRIPTION

Detailed embodiments of the claimed structures and methods are disclosedherein; however, it can be understood that the disclosed embodiments aremerely illustrative of the claimed structures and methods that may beembodied in various forms. This invention may, however, be embodied inmany different forms and should not be construed as limited to theexemplary embodiments set forth herein. In the description, details ofwell-known features and techniques may be omitted to avoid unnecessarilyobscuring the presented embodiments.

References in the specification to “one embodiment”, “an embodiment”,“an example embodiment”, etc., indicate that the embodiment describedmay include a particular feature, structure, or characteristic, butevery embodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

It will be understood that when an element as a layer, region orsubstrate is referred to as being “on” or “over” another element, it canbe directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” or “directly over” another element, there are no interveningelements present. It will also be understood that when an element isreferred to as being “connected” or “coupled” to another element, it canbe directly connected or coupled to the other element or interveningelements may be present. In contrast, when an element is referred to asbeing “directly connected” or “directly coupled” to another element,there are no intervening elements present. Also the term“sub-lithographic” may refer to a dimension or size less than currentdimensions achievable by photolithographic processes, and the term“lithographic” may refer to a dimension or size equal to or greater thancurrent dimensions achievable by photolithographic processes. Thesub-lithographic and lithographic dimensions may be determined by aperson of ordinary skill in the art at the time the application isfiled.

In the interest of not obscuring the presentation of embodiments of thepresent invention, in the following detailed description, someprocessing steps or operations that are known in the art may have beencombined together for presentation and for illustration purposes and insome instances may have not been described in detail. In otherinstances, some processing steps or operations that are known in the artmay not be described at all. It should be understood that the followingdescription is rather focused on the distinctive features or elements ofvarious embodiments of the present invention.

The present invention generally relates to semiconductor manufacturing,and more particularly to fabricating electrically insulated contacts ofa logic device and a strapped contact of a static random access memory(hereinafter “SRAM”) device in the same process flow. One way tofabricate both the electrically insulated contacts and the strappedcontact may include fabricating and manipulating a pair of sidewallspacers when forming the gate contacts of both the SRAM device and thelogic device. One method of fabricating and manipulating the pair ofsidewall spacers to produce the electrically insulated contacts of thelogic device and the strapped contact of the SRAM device is described indetail below by referring to the accompanying drawings in FIGS. 1-15, inaccordance with an illustrative embodiment.

Referring now to FIG. 1, a semiconductor structure 100 (hereinafter“structure”) is shown according to an exemplary embodiment. In general,the structure 100 may include a dielectric layer 112 formed on top of asubstrate 102. Also, the structure 100 may be described as including anSRAM device region 300 and a logic device region 400. The dielectriclayer 112 may also be referred to as a middle-of-line (hereinafter“MOL”) dielectric.

The structure 100 of FIG. 1 may be formed or provided. At this step ofthe manufacturing process, the beginning structures of an SRAM device302 and a logic device 402 are shown. The SRAM device 302 and the logicdevice 402 may preferably be fabricated in the SRAM device region 300and the logic device region 400, respectively. At this step of themanufacturing process both the SRAM device 302 and the logic device 402may include sidewall spacers 104, a gate dielectric layer 106, a gateelectrode or a gate 108, and a gate cap 110. The SRAM device 302 and thelogic device 402 may be formed on the substrate 102 as shown in FIG. 1according to techniques known in the art.

The SRAM device 302 and the logic device 402 may be fabricated usingeither a replacement gate or gate last process flow, or a gate firstprocess flow. A replacement gate process flow will be relied on for thedescription provided below.

In a replacement gate (RG) fabrication approach, the semiconductorsubstrate 102 may be patterned and etched to form active device region(e.g., fins). Next, one or more dummy gates may be formed in a directionperpendicular to the length of the fins. For example, the dummy gatesmay be pattered and etched from a polysilicon layer. A pair of sidewallspacers, for example, the sidewall spacers 104, can be disposed onopposite sidewalls of the dummy gates. The dummy gates and the pair ofsidewall spacers may then be surrounded by an inter-level dielectric.Later, the dummy gates may be removed from between the pair of devicespacers, as by, for example, an anisotropic vertical etch process suchas a reactive ion etch (RIE). This creates an opening between the pairof device spacers where a metal gate, for example, the gate 108, maythen be formed between the pair of device spacers. Optionally, a gatedielectric, for example, the gate dielectric layer 106, may beconfigured below the metal gate.

The substrate 102 may be a bulk substrate, which may be made from any ofseveral known semiconductor materials such as, for example, silicon,germanium, silicon-germanium alloy carbon-doped silicon-germanium alloy,and compound (e.g. III-V and II-VI) semiconductor materials.Non-limiting examples of compound semiconductor materials includegallium arsenide, indium arsenide, and indium phosphide. In otherembodiments, the substrate 102 may be, for example, a layeredsemiconductor such as Si/SiGe, a silicon-on-insulator, or aSiGe-on-insulator, where a buried insulator layer separates a basesubstrate from a top semiconductor layer. In such cases, components ofthe structure 100 may be formed in or from the top semiconductor layerof the SOI substrate. Typically the substrate 102 may be approximately,but is not limited to, several hundred microns thick.

In an embodiment, the SRAM device 302 and the logic device 402 may befabricated as FinFET devices, nanowire devices, planar MOSFETs, or anysuitable combination of those devices. In general, a FinFET device mayinclude a plurality of fins formed in the substrate 102. In the presentembodiment, the gates 108, of both the SRAM device 302 and the logicdevice 402 may each be perpendicular to and cover a portion of one ormore fins. The portion of the fin covered by the gates 108 may serve asa channel region of each device (302, 402). Portions of the finextending out from under each of the gates 108 may serve as source anddrain regions for each device (302, 402). In this example, the FinFETmay be formed from the semiconductor substrate 102 using knownphotolithography and etch processes. It should be noted that the gatedielectric layer 106 may, in most cases, separate the gate 108 from thechannel regions in the fin. It should also be noted, that in the contextof FinFET devices the portion of the substrate 102 illustrated in thefigures represents a cross-section view of a fin and the gate dielectriclayer 106 and the gate 108 are illustrated as being disposed directly ontop of the fin, according to the present embodiment.

The dielectric layer 112 may be formed directly on the exposed topsurfaces of the structure 100, according to an exemplary embodiment. Thedielectric layer 112 may be made from an insulator material such as anoxide, nitride, oxynitride, silicon carbon oxynitride, silicon boronoxynitride, low-k dielectric, or any combination thereof. The dielectriclayer 112 may be deposited using typical deposition techniques, forexample, atomic layer deposition (ALD), molecular layer deposition(MLD), chemical vapor deposition (CVD), physical vapor deposition (PVD),and spin on techniques. In an embodiment, the dielectric layer 112 mayinclude one or more layers. In an embodiment, the dielectric layer 112may have a vertical thickness, or height, ranging from about 20 nm to200 nm, and ranges there between, although a thickness less than 20 nmand greater than 200 nm may be acceptable.

The gate dielectric layer 106 may be formed using typical depositiontechniques, for example, atomic layer deposition (ALD), molecular layerdeposition (MLD), chemical vapor deposition (CVD), physical vapordeposition (PVD), or any suitable combination of those techniques. Thematerial of the gate dielectric 106 may include silicon oxide, siliconnitride, silicon oxynitride, boron nitride, high-k materials, or anycombination of these materials. Examples of high-k materials include butare not limited to metal oxides such as hafnium oxide, hafnium siliconoxide, hafnium silicon oxynitride, lanthanum oxide, lanthanum aluminumoxide, zirconium oxide, zirconium silicon oxide, zirconium siliconoxynitride, tantalum oxide, titanium oxide, barium strontium titaniumoxide, barium titanium oxide, strontium titanium oxide, yttrium oxide,aluminum oxide, lead scandium tantalum oxide, and lead zinc niobate. Thehigh-k may further include dopants such as lanthanum, aluminum. In anembodiment, the gate dielectric layer 106 may include hafnium oxidedeposited using a chemical vapor deposition technique.

The gate 108 may be formed using known techniques. The material of thegate 108 may include polycrystalline or amorphous silicon, germanium,silicon germanium, a metal (e.g., tungsten, titanium, tantalum,ruthenium, zirconium, cobalt, copper, aluminum, lead, platinum, tin,silver, gold), a conducting metallic compound material (e.g., tantalumnitride, titanium nitride, tungsten silicide, tungsten nitride,ruthenium oxide, cobalt silicide, nickel silicide), carbon nanotube,conductive carbon, or any suitable combination of these materials. Theconductive material may further comprise dopants that are incorporatedduring or after deposition.

In an embodiment, the gate cap 110 may be fabricated atop the gate 108,an exposed edge of the gate dielectric layer 106 and an exposed edge ofthe sidewall spacers 104. The gate cap 110 may include any dielectricmaterial known in the art, for example, a nitride. The gate cap 110 maybe deposited using typical deposition techniques, for example, atomiclayer deposition (ALD), molecular layer deposition (MLD), chemical vapordeposition (CVD), physical vapor deposition (PVD), and spin ontechniques. The gate cap 110 may include silicon nitride deposited usinga chemical vapor deposition technique. The gate cap 110 may have athickness ranging from about 5 nm to about 30 nm and ranges therebetween, although a thickness less than 5 nm and greater than 30 nm maybe acceptable. Preferably, the gate cap 110 is provided to protect thegate 108, the exposed edge of the gate dielectric layer 106 and theexposed edge of the sidewall spacers 104 during subsequent processing.As such, the gate cap 110 may typically be composed of a material whichhas a different etch rate than the dielectric layer 112. Morespecifically, the dielectric layer 112 may preferably be composed of amaterial which may be etched and removed selective to the gate cap 110.Furthermore, the gate cap 110 may function as an etch stop duringsubsequent processing techniques.

It should be noted that the area of the substrate 102, or fin, coveredby the gate 108 may generally be referred to as a gate electrode, andthe areas of the substrate 102, or fin, not covered by the gate 108 maygenerally be referred to as a source drain region. It should be notedthat any number of gates 108 may be formed on the structure 100.

Referring now to FIG. 2, a first opening 130 and a second opening 132may be formed using standard patterning, lithography and etchtechniques. The first opening 130 may be located in the SRAM deviceregion 300 and is generally aligned with the SRAM device 302, and thesecond opening 132 may be located in the logic device region 400 and isgenerally aligned with the logic device 402. Stated differently, thefirst opening 130 may be self-aligned to the sidewall spacer 104 andgate cap 110 of the SRAM device and the second opening 132 may beself-aligned to the sidewall spacer 104 and the gate cap 110 of thelogic device. The first and second openings 130, 132 may each be aself-aligned contact, where the gate cap 110 and the sidewall spacer 104border a side of the first and second openings 130, 132, and may form anetch stop during the standard patterning, lithography and etchtechniques. The substrate 102 may preferably be exposed at a bottom ofboth the first opening 130 and the second opening 132. Morespecifically, the first opening 130 and the second opening 132 maypreferably expose the source drain region of the SRAM device 302 and thelogic device 402, respectively.

Due to dimensional constraints and motivations to conserve valuablearea, the first and second openings 130, 132, may coincide with orintersect the SRAM device 302 and the logic device 402, respectively, asillustrated. The first and the second openings 130, 132, may expose asource drain region of the SRAM device 302, and a source drain region ofthe logic device 402, respectively. The first and the second openings130, 132, may extend over a top portion of the gate cap 110, and mayexpose a sidewall of the sidewall spacer 104 of the SRAM device 302 andthe logic device 402, respectively. A bottom of the first opening 130and a bottom of the second opening 132 may range from about 10 nm toabout 100 nm wide, and ranges there between, although a width less than10 nm and greater than 100 nm may be acceptable. A top of the firstopening 130 and a top of the second opening 132 may range from about 10nm to about 30 nm wider than the bottoms of the first opening 130 andthe second opening, respectively.

It should be noted that in forming the first opening 130 and the secondopening 132, portions of the dielectric layer 112 may be removedselective to both the sidewall spacers 104 and the gate cap 110.Likewise, the sidewall spacers 104 and the gate cap 110 may serve toprotect the gate 108 during etching of the first and second openings130, 132.

Referring now to FIG. 3, a first opening liner 140 and a first contact144 may be formed in the first opening 130, and a second opening liner142 and a second contact 146 may be formed in the second opening 132.The first opening liner 140 and the second opening liner 142 may befirst deposited using typical deposition techniques, for example, atomiclayer deposition (ALD), molecular layer deposition (MLD), chemical vapordeposition (CVD), physical vapor deposition (PVD), and spin ontechniques. In an embodiment, the first opening liner 140 and the secondopening liner 142 may include titanium nitride (TiN) deposited using achemical vapor deposition technique. In an embodiment, the first openingliner 140 and the second opening liner 142 may have a thickness rangingfrom about 2 nm to about 5 nm and ranges there between, although athickness less than 2 nm and greater than 5 nm may be acceptable.

The first contact 144 and the second contact 146 may be a conductingmaterial, such as metal. For example, the first contact 144 and thesecond contact 146 may be tungsten (W), copper (Cu), or cobalt (Co) andmay be deposited using typical deposition techniques, for example,atomic layer deposition (ALD), molecular layer deposition (MLD),chemical vapor deposition (CVD), physical vapor deposition (PVD), andspin on techniques. The first opening liner 140, the second openingliner 142, the first contact 144 and the second contact 146 may bepolished using a chemical mechanical polishing (CMP) technique until atop surface of each of the first opening liner 140, the second openingliner 142, the first contact 144 and the second contact 146 issubstantially coplanar with a top surface of the dielectric layer 112,as illustrated. Stated differently, top surfaces of each of the firstopening liner 140, the second opening liner 142, the first contact 144and the second contact 146 are substantially flush with a top surface ofthe dielectric layer 112.

Referring now to FIG. 4, a third opening 150 and a fourth opening 152may be formed using standard patterning, lithography and etchtechniques. The third opening 150 may be located in the SRAM deviceregion 300 and is generally aligned with the SRAM device 302. The fourthopening 152 may be located in the logic device region 400 and isgenerally aligned with the logic device 402. The third and fourthopenings 150, 152, may each be a self-aligned contact, where the firstand second openings liner 140, 142, border a portion of a side of thethird and fourth openings 150, 152, and may form an etch stop during thestandard patterning, lithography and etch techniques. A portion of thegate cap 110 may be removed in the SRAM device and in the logic device402, exposing a top surface of the gate 108, an exposed top surface ofthe gate dielectric layer 106 and an exposed top surface of the sidewallspacer 104, of the SRAM device 302 and the logic device 402,respectively. A portion of the gate cap 110 of the SRAM device 302 andthe logic device 402 may remain, as illustrated. The third and fourthopenings 150, 152, may expose a sidewall portion of the first openingliner 140 and the second opening liner 142 of the SRAM device 302 andthe logic device 402, respectively.

Referring now to FIG. 5, a first pair of sidewall spacers 160 may beformed within the third opening 150, and a second pair of sidewallspacers 162 may be formed within the fourth opening 152. In general, thefirst and second pairs of sidewall spacers 160, 162, may be formed onopposite sidewalls of the third and fourth openings 150, 152,respectively. The first and second pairs of sidewall spacers 160, 162may be formed by conformally depositing or growing a dielectric,followed by an anisotropic etch that removes the dielectric from thehorizontal surfaces of the structure 100, while leaving it on thesidewalls of the third and fourth openings 150, 152. In an embodiment,the first and second pairs of sidewall spacers 160, 162 may include anydielectric material such as silicon oxide, silicon oxynitride, siliconnitride, SiBCN, SiOC, low-k dielectric or any combination of thesematerials. The first and second pairs of sidewall spacers 160, 162, mayinclude a single layer; however, the first and second pairs of sidewallspacers 160, 162, may include multiple layers of dielectric material. Inan embodiment, the first and second pairs of sidewall spacers 160, 162,may be silicon nitride. In an embodiment, the first and second pairs ofsidewall spacers 160, 162, may have a lateral thickness ranging fromabout 3 nm to about 20 nm, and ranges there between, although athickness less than 3 nm and greater than 20 nm may be acceptable. Thefirst and second pairs of sidewall spacers 160, 162 may serve toinsulate the gate from the source drain region.

Referring now to FIG. 6, the first pair of sidewall spacers 160 may berecessed while protecting the logic device 402 and the second pair ofsidewall spacers 162 using a mask 170. First, the mask 170 may be formedin the logic device region 400 to cover and protect the second pair ofsidewall spacers 162. The mask 170 may be a hardmask formed using knownphotolithography and etch processes. The mask 170 may directly cover thelogic device 402 in the logic device region 400. The SRAM device region300 may not be covered by the mask 170. A directional etch, for examplean anisotropic vertical etch process such as a reactive ion etch (RIE),may be performed in the SRAM device region 300, and may remove an upperportion of the first pair of sidewall spacers 160 on both a first sideof the third opening 150 and a second side of the third opening 150. Ina preferred embodiment, a portion of the sidewall spacer 104 and aportion of the gate dielectric layer 106, both in the SRAM device 302,may be removed, exposing a portion of a sidewall of the gate 108 of theSRAM device 302.

Referring now to FIG. 7, the mask 170 may be removed. The mask 170 maybe removed by known etch processes. As shown in the figure, a thirdopening liner 180, a fourth opening liner 182, a third contact 184 and afourth contact 186 may be formed. The third and fourth opening liners180, 182, may be deposited using typical deposition techniques, forexample, atomic layer deposition (ALD), molecular layer deposition(MLD), chemical vapor deposition (CVD), physical vapor deposition (PVD),and spin on techniques, followed by a directional etch, for example ananisotropic vertical etch process such as a reactive ion etch (RIE). Inan embodiment, the third and fourth opening liners 180, 182, may includetitanium nitride (TiN) deposited using a chemical vapor depositiontechnique. In an embodiment, the third and fourth opening liners 180,182, may include one or more layers. The third and fourth opening liners180, 182, may be conformally formed on exposed surfaces of the third andfourth openings 150, 152, respectively. In an embodiment, the third andfourth opening liners 180, 182, may have a thickness, about 3 nm to 20nm, and ranges there between, although a thickness less than 3 nm andgreater than 20 nm may be acceptable.

The third and fourth contacts 184, 186, may be a conducting material,such as a metal. In an embodiment, the third and fourth contacts 184,186, may be tungsten (W), copper (Cu), or cobalt (Co), and may bedeposited using typical deposition techniques, for example, atomic layerdeposition (ALD), molecular layer deposition (MLD), chemical vapordeposition (CVD), physical vapor deposition (PVD), and spin ontechniques. The third and fourth opening liners 180, 182, and the thirdand fourth contacts 184, 186, may be polished using a chemicalmechanical polishing (CMP) technique until a top surface of third andfourth opening liners 180, 182, and the third and fourth contacts 184,186, are substantially coplanar with a top surface of the dielectriclayer 112, as illustrated. Stated differently, top surfaces of each ofthe third opening liner 180, the fourth opening liner 182, the thirdcontact 184 and the fourth contact 186 are substantially flush with atop surface of the dielectric layer 112.

As illustrated, the first contact 144, the first opening liner 140, thethird opening liner 180 and the third contact 184, are electricallyconnected and a conductive path exists between the gate 108 and thesource/drain of the SRAM device 302. The conductive path between thegate 108 and the source/drain of the SRAM device 302 may be referred toas a strapped contact. The strapped contact creates an electricalconnection between the source drain region of the SRAM device and thegate 108 of the SRAM device, the electrical connection is directly abovea remaining portion of the first pair of sidewall spacers 160.

Together, the second contact 146 and the second opening liner 142, areseparated from the fourth contact 186 and the fourth opening liner 182by a portion of the second pair of sidewall spacers 162. This provides anon-conductive path between the gate 108 and source/drain of the logicdevice region 400. The gate 108 and the source/drain of the logic device402 are electrically insulated. The first, second, third and fourthcontacts 144, 146, 184, 186, may be within the MOL dielectric.

The previous descriptions refer to the fabrication of an SRAM and alogic device. The process as described can be used for any semiconductorfabrication which has devices which requires both connected gate andsource drain regions, and non-connected gate and source drain regions.

Referring now to FIG. 8, a top view of the structure 100 is shown. Theline AA depicts a cross sectional line of the FIGS. 1 to 7. The gate 108of both the SRAM device 302 and the logic device 402 is depicted withdashed lines for added clarity and understanding. The dielectric layer112 may electrically insulate the contacts of the SRAM device 302 fromthe contacts of the logic device 402. The first contact 144 and thefirst opening liner 140 make up the contact for the source/drain of theSRAM device 302. The third contact 184 and the third opening liner 180make up the contact for the gate 108 of the SRAM device 302. The firstand third contacts 144, 184, and the first and third opening liners 140,180, are all electrically connected. Thus, the gate 108 of the SRAMdevice 302 is electrically connected to the source/drain of the SRAMdevice 302. A fifth contact 220 and a fifth opening liner 222 make upanother source drain contact for the SRAM device 302, which iselectrically insulated from both the first contact 144 and the thirdcontact 184.

The second contact 146 and the second opening liner 142 make up thecontact for the source/drain of the logic device 402. The fourth contact186 and the fourth opening liner 182 make up the contact for the gate108 of the logic device 402. A sixth contact 224 and a sixth openingliner 226 make up a contact for another source/drain of the logic device402. The contacts for the gate 108 and both source/drains of the logicdevice 402 are each electrically insulated from one another.Specifically, a portion of the sidewall spacer 162 electricallyinsulates the second contact 146 from the fourth contact 186.

An alternate embodiment of this invention follows FIGS. 1 to 2 andcontinues with FIG. 9. In this alternate embodiment, the first andsecond openings 130, 132 are filled with a sacrificial material which islater removed. The first, second, third and fourth openings, 130, 132,150, 152, are later filled with a liner and a contact. The process stepsare substantially similar to above, with like numbered objects the sameas the above description.

Referring now to FIG. 9, a first sacrificial filler 190 and a secondsacrificial filler 192 may be formed in the first opening 130 and thesecond opening 132, respectively. The first and second sacrificialfillers 190, 192, may include any suitable silicon or polysilicon ableto be selectively removed relative to other materials used in thisembodiment for an opening liner, a spacer, a gate cap, a dielectric,etc. In an embodiment, the first and second sacrificial fillers 190,192, may include amorphous carbon. The first and second sacrificialfillers 190, 192, may be deposited using typical deposition techniques,for example, atomic layer deposition (ALD), molecular layer deposition(MLD), chemical vapor deposition (CVD), physical vapor deposition (PVD),and spin on techniques. In some embodiments, a thin layer of dummy oxide(not shown) may be deposited prior to depositing the first and secondsacrificial fillers 190, 192. The first and second sacrificial fillers190, 192, may be polished using a chemical mechanical polishing (CMP)technique until a top surface of the first and second sacrificialfillers 190, 192 is substantially coplanar with a top surface of thedielectric layer 112, as illustrated. Stated differently, top surfacesof each of the first and second sacrificial fillers 190, 192 aresubstantially flush with a top surface of the dielectric layer 112.

Referring now to FIG. 10, a third opening 150 and a fourth opening 152may be formed using standard patterning, lithography and etchtechniques. The third opening 150 may be located in the SRAM deviceregion 300 and is generally aligned with the SRAM device 302. The fourthopening 152 may be located in the logic device region 400 and isgenerally aligned with the logic device 402. A portion of the gate cap110 may be removed in the SRAM device and in the logic device 402,exposing a top surface of the gate 108, an exposed top surface of thegate dielectric layer 106 and an exposed top surface of the sidewallspacer 104, of the SRAM device 302 and the logic device 402,respectively. A portion of the gate cap 110 of the SRAM device 302 andthe logic device 402 may remain, as illustrated. The third and fourthopenings 150, 152, may expose a sidewall portion of the first openingliner 140 and the second opening liner 142 of the SRAM device 302 andthe logic device 402, respectively.

Referring now to FIG. 11, a first pair of sidewall spacers 160 may beformed within the third opening 150, and a second pair of sidewallspacers 162 may be formed within the fourth opening 152. In general, thefirst and second pairs of sidewall spacers 160, 162, may be formed onopposite sidewalls of the third and fourth openings 150, 152,respectively. The first and second pairs of sidewall spacers 160, 162,may be formed by conformally depositing or growing a dielectric,followed by an anisotropic etch that removes the dielectric from thehorizontal surfaces of the structure 100, while leaving it on thesidewalls of the third and fourth openings 150, 152. In an embodiment,the first and second pairs of sidewall spacers 160, 162, may include anydielectric material such as silicon nitride (Si3N4), SiBCN, SiOC, low-kdielectric or any combination of these materials. The first and secondpairs of sidewall spacers 160, 162, may include a single layer; however,the first and second pairs of sidewall spacers 160, 162, may includemultiple layers of dielectric material. In an embodiment, the first andsecond pairs of sidewall spacers 160, 162, may be silicon nitride (SiN).In an embodiment, the first and second pairs of sidewall spacers 160,162, may have a lateral thickness ranging from about 3 nm to about 20nm, and ranges there between, although a thickness less than 3 nm andgreater than 20 nm may be acceptable. The first and second pairs ofsidewall spacers 160, 162 may serve to insulate the gate from the sourcedrain region.

Referring now to FIG. 12, the first pair of sidewall spacers 160 may berecessed while protecting the logic device 402 and the second pair ofsidewall spacers 162 using a mask 170. First, the mask 170 may be formedin the logic device region 400 to cover and protect the second pair ofsidewall spacers 162. The mask 170 may be a hardmask formed using knownphotolithography and etch processes. The mask 170 may directly cover thelogic device region 400. The SRAM device region 300 may not be coveredby the mask 170. A directional etch, for example an anisotropic verticaletch process such as a reactive ion etch (RIE), may be performed in theSRAM device region 300, and may remove an upper portion of the firstpair of sidewall spacers 160 on both a first side of the third opening150 and a second side of the third opening 150. In a preferredembodiment, a portion of the sidewall spacer 104 and a portion of thegate dielectric layer 106, both in the SRAM device 302, may be removed,exposing a portion of a sidewall of the gate 108 of the SRAM device 302.

Referring now to FIG. 13, the mask 170 may be removed. The mask 170 maybe removed by known etch processes. The first and second sacrificialfillers 190, 192, may also be removed by known etch processes relativeto other materials used in this embodiment, exposing the first andsecond openings 130, 132.

Referring now to FIG. 14, a first opening liner 140 and a first contact144 may be formed in the first opening 130 and in the third opening 150.A second opening liner 142 and a second contact 146 may be formed in thesecond opening 132. A fourth opening liner 182 and a fourth contact 186may be formed in the fourth opening 152.

The first, second and fourth opening liners 140, 142, 182, may bedeposited using typical deposition techniques, for example, atomic layerdeposition (ALD), molecular layer deposition (MLD), chemical vapordeposition (CVD), physical vapor deposition (PVD), and spin ontechniques, followed by a directional etch, for example an anisotropicvertical etch process such as a reactive ion etch (RIE). In anembodiment, the first, second and fourth opening liners 140, 142, 182,may include titanium nitride (TiN) deposited using a chemical vapordeposition technique. In an embodiment, the first, second and fourthopening liners 140, 142, 182, may include one or more layers. The first,second and fourth opening liners 140, 142, 182, may be conformallyformed on exposed surfaces of the openings (130 and 150), 132, 152,respectively. In an embodiment, the first, second and fourth openingliners 140, 142, 182, may have a thickness, about 3 nm to 20 nm, andranges there between, although a thickness less than 3 nm and greaterthan 20 nm may be acceptable.

The first, third and fourth contacts 144, 146, 186, may be a conductingmaterial, such as a metal. In an embodiment, the first, third and fourthcontacts 144, 146, 186, may be tungsten (W), and may be deposited usingtypical deposition techniques, for example, atomic layer deposition(ALD), molecular layer deposition (MLD), chemical vapor deposition(CVD), physical vapor deposition (PVD), and spin on techniques. Thefirst, second and fourth opening liners 140, 142, 182, and the first,third and fourth contacts 144, 146, 186, may be polished using achemical mechanical polishing (CMP) technique until a top surface offirst, second and fourth opening liners 140, 142, 182, and the first,third and fourth contacts 144, 146, 186, is substantially coplanar witha top surface of the dielectric layer 112, as illustrated. Stateddifferently, top surfaces of each of the first, second and fourthopening liners 140, 142, 182, and the first, third and fourth contacts144, 146, 186, are substantially flush with a top surface of thedielectric layer 112. In other words, the first, third and fourthcontacts 144, 146, 186, may all be within the MOL dielectric.

As illustrated, the first contact 144 and the first opening liner 140provide a conductive path between the gate 108 of the SRAM device andthe source/drain of the SRAM device 302. The first contact 144 mayalternatively be referred to as a strapped contact.

Together, the second contact 146 and the second opening liner 142, areseparated from the fourth contact 186 and the fourth opening liner 182by a portion of the second pair of sidewall spacers 162. Therefore, theportion of the pair of sidewall spacers 162 isolates or electricallyinsulates the gate 108 from the source/drain of the logic device 402.

Referring now to FIG. 15, a top view of the structure 100 is shown. Theline AA depicts a cross sectional line of the FIGS. 1, 2, 9 to 14. Thegate 108 of both the SRAM device 302 and the logic device 402 isdepicted with dashed lines for added clarity and understanding. Thedielectric layer 112 may electrically insulate the contacts of the SRAMdevice 302 from the contacts of the logic device 402. The first contact144 and the first opening liner 140 make up the contact for both thegate 108 and the source/drain of the SRAM device 302. Thus, the gate 108of the SRAM device 302 is electrically connected to the source/drain ofthe SRAM device 302. A fifth contact 220 and a fifth opening liner 222make up another source drain contact for the SRAM device 302, which iselectrically insulated from the first contact 144.

The second contact 146 and the second opening liner 142 make up thecontact for the source/drain of the logic device 402. The fourth contact186 and the fourth opening liner 182 make up the contact for the gate108 of the logic device 402. A sixth contact 224 and a sixth openingliner 226 make up a contact for another source/drain of the logic device402. The contacts for the gate 108 and both source/drains of the logicdevice 402 are each electrically insulated from one another.Specifically, a portion of the sidewall spacer 162 electricallyinsulates the second contact 146 from the fourth contact 186.

The previous descriptions refer to the fabrication of an SRAM and alogic device. The process as described can be used for any semiconductorfabrication which has devices which requires both connected gate andsource drain regions, and non-connected gate and source drain regions.

As the semiconductor industry evolves, there is a benefit to reduce orcombine semiconductor manufacturer process steps. The present inventionmay allow for the manufacture of devices requiring electricallyinsulated contacts, as in a logic device, and devices requiring strappedor connected devices, as in an SRAM device. Two embodiments of thisinvention as described above, describe the fabrication of openings andcontacts for the gate and the source/drain regions of each device and amethod to form a connected gate and source/drain in some devices, whilea pair of sidewall spacers may electrically insulate the gate andsource/drain of other devices.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the invention.The terminology used herein was chosen to best explain the principles ofthe embodiment, the practical application or technical improvement overtechnologies found in the marketplace, or to enable others of ordinaryskill in the art to understand the embodiments disclosed herein.

What is claimed is:
 1. A method comprising: forming a first opening in adielectric layer which exposes a source drain region of an SRAM deviceand forming a second opening in the dielectric layer which exposes asource drain region of a logic device; forming a third opening in thedielectric layer which exposes a gate of the SRAM device and forming afourth opening in the dielectric layer which exposes a gate of the logicdevice; forming a first sidewall spacer in the third opening and forminga second sidewall spacer in the fourth opening; recessing a portion ofthe first sidewall spacer in the third opening without recessing thesecond sidewall spacer in the fourth opening; forming a strapped contactin the first and third openings, wherein the strapped contact creates anelectrical connection between the source drain region of the SRAM deviceand the gate of the SRAM device, wherein the electrical connection isdirectly above a remaining portion of the first sidewall spacer in thethird opening; and forming contacts in the second and fourth openings,wherein the second sidewall spacer in the fourth opening electricallyisolates the contact of the second opening from the contact of thefourth opening, wherein recessing a portion of the first sidewall spacerin the third opening without recessing the second sidewall spacer in thefourth opening further comprises deposition of a hard mask in the regionof the logic device, recessing a portion of the first sidewall spacer inthe third opening, and removal of the hard mask.
 2. The method accordingto claim 1, wherein forming the first opening intersects the SRAM deviceand forming the second opening intersects the logic device.
 3. Themethod according to claim 1, wherein forming the third opening furthercomprises: recessing a portion of a gate sidewall spacer of the SRAMdevice; and recessing a portion of a gate dielectric layer of the SRAMdevice.
 4. The method according to claim 1, wherein the SRAM device andthe logic device are both FinFETs.
 5. The method according to claim 1,wherein the gates of the SRAM device and the logic device comprise agate dielectric of titanium nitride.
 6. The method according to claim 1,wherein forming the first and the second openings further comprisesrecessing the dielectric layer over a top portion of a gate cap, in boththe SRAM device and the logic device.
 7. The method according to claim1, further comprising: filling both the first opening and the secondopening with a sacrificial material; removing the sacrificial materialfrom within both the first opening and the second opening.
 8. A methodcomprising: forming a first opening in a dielectric layer which exposesa source drain region of an SRAM device and forming a second opening inthe dielectric layer which exposes a source drain region of a logicdevice; forming a first contact in the first opening and forming asecond contact in the second opening; forming a third opening in thedielectric layer which exposes a gate of the SRAM device and a sidewallof the first contact in the first opening, and forming a fourth openingin the dielectric layer which exposes a gate of the logic device;forming a first sidewall spacer in the third opening and forming asecond sidewall spacer in the fourth opening, the first sidewall spacerin the third opening being in direct contact with the sidewall of thefirst contact in the first opening; recessing a portion of the firstsidewall spacer in the third opening to expose the sidewall of the firstcontact in the first opening, without recessing the second sidewallspacer in the fourth opening; forming a third contact in the thirdopening, abutting the sidewall of the first contact in the firstopening, such that the source drain region of the SRAM device is inelectrical contact with the gate of the SRAM device; and forming afourth contact in the fourth opening, wherein the second sidewall spacerin the fourth opening electrically isolates the second contact in thesecond opening from the fourth contact in the fourth opening, whereinrecessing a portion of the first sidewall spacer in the third openingwithout recessing the second sidewall spacer in the fourth openingfurther comprises deposition of a hard mask in the region of the logicdevice, recessing a portion of the first sidewall spacer in the thirdopening, and removal of the hard mask.
 9. The method according to claim8, wherein forming the first opening intersects the SRAM device andforming the second opening intersects the logic device.
 10. The methodaccording to claim 8, wherein forming the third opening furthercomprises: recessing a portion of a gate sidewall spacer of the SRAMdevice; and recessing a portion of a gate dielectric layer of the SRAMdevice.
 11. The method according to claim 8, wherein the SRAM device andthe logic device are both FinFETs.
 12. The method according to claim 8,wherein the gates of the SRAM device and the logic device comprise agate dielectric of titanium nitride.
 13. The method according to claim8, wherein forming the first and second openings further comprisesrecessing the dielectric layer over a top portion of a gate cap, in boththe SRAM device and the logic device.